Mixture of polychloroprene, vinyl chloride-vinylidene chloride copolymer, and butadiene-acrylonitrile copolymer



Patented Nov. 3, 1953 UNITED STATES PATENT Ralph- J. signers Chicago, and Keith F. Bea], Park Forest, 111., assignors to The Visking Corporation,Chicag o, 111., a corporation ofVirginia N'o. Drawing. Original application January 14,

1941:, Serial No. 7223082. Dividedw and. thisapplication June 8., 1950, Serial No. 166,974.

4' Claims. (Cl. 260-455) This invention, which. is a division of copending application Ser. No. 722,082, filed January 14, 1947, now U. S. Patent No. 2,547,605, relates tov resinous compositions, and formed Structures produced therefrom. More. particularly, it relates to a new, and improvedsynthetic resin composition and formed structures produced therefrom Many synthetic resins, such as, for example, vinylidene chloride acrylonitrile 'copolymer, vinylidene chloride-vinyl chloridec po ym r, p lychloroprene, 1,3 butadiene acrylonitrile copolymer, vinylchloride-vinyl acetate copolymer, vinyl chloride-acrylonitrile copolymer, polyvinylidene chloride, etc. are. currently and commercially available. A film produced from any of the aforementioned synthetic resins does not possess the necessary properties of v flexibility, high resistance to tear, highelongation. capacity to return after elongation, high tensilestrength high resistance to moisture vapor penetration and to penetration, by gases, as are required for the packaging of foodstuffs. Attempts were made to improve the physical. properties of such; films by the incorporation of a liquid. plasticizer in the composition. from which the films are produced. However, films containing a, liquid plasticizer are unsatisfactory for the reason that such liquid plasticizers migrate fromthe resin or disappear by evaporation, leaving. theresin embrittled, and frequently contaminatethecontents of the package especially if the contents of the package is a foodstuff.

In the course of research to mprove the properties of films produced; from synthetic resins mentioned, attempts were made. to prepare films oi resinous compositions. containing a plurality of synthetic resins. However, when attempts were made to form a resinous composition of butadiene-acrylonitrile. copolymer and vinylidene chloride-vinyl chloride copolymer it was found that, such, resins were incompatible.

An object of this invention is to make a plu: rality of resins, which are normally incompatible in desired proportions, compatible Another object of: thisinvention is to provide a resinous composition containing a, plurality of resins normally, incompatible in the desired proportions and a blending agent which will make such resins compatible.

An additionalobiect of this invention is topmvide formed structures formed of normally incompatible resins butv which. are compatible in the structure.

A further object of: this invention is to provide resinous formed structures having improved physical properties.

A specific object of this invention is to provide films formed of resinous compositions having physical properties which render them suitable for use as a packaging material.

Other and additional objects willbecome apparent hereinafter.

The above objects; are accomplished, in general. by incorporating in a resinous. comp0sition..oon.- taining a plurality of synthetic resins in proportions at which such resins are normally incompatible but which are necessary to obtain the desired properties, a blending agent whereby a homogeneous resinous composition is obtained from which the desiredformedstructureis. prepared and in which structure the synthetic resins are compatible.

The blending agent, in general, is a. synthetic resin as will hereinafter be morefully explained.

Usually, the synthetic resin components and the blending agent are dissolved in a solvent or solvent mixture whereby a homogeneous solution is obtained. Herein the..term solventf covers a. single solvent or a solvent mixture. N0 precise sequence for dissolving the resins and blending agent in the solvent is required. The resin components and blending agent can be added separately or simultaneously to the sol,- vent. After the desired solution has been. prepared, it is processed. depending, on the desired formed structure. Inone embodiment of the-invention, the resinous composition is formed into the desired formed structure and the solvent evaporated therefrom. In. another embodiment, the resinous composition is extruded or cast into a precipitating bath, in which the resins. are in-r soluble and with which the solventis miscible, and thereafter the precipitated. resinous article dried.

The nature of the invention will become more apparent byreference to the examples herein.- after set forth, wherein. the proportions are by weight. It isto be understood thatthe examples are merely illustrative embodiments of the in? vention andthat thescopeoi theinvention is not restricted. thereto. For convenience, thespecific synthetic resins and specific, blending agents'of the examples are designatedby. their respective 3 trade names, the identity of which is set forth in the following table:

TABLE I Trade-name Made and sold byzgggggggl 82% vinylidene Saran 13-118... Dow Chemical Co chloride.

18% vinyl chloride. Neoprene CG. E.CI. du Pont de Nemours & 100% chloroprene.

Hyccr 011-15. B. F. Goodrich Co ggfigfgf EXAMPLE 1 parts Neoprene CG, 10 parts Hycar OR-l5, and 20 parts Saran B-l18 were dissolved in 160 parts tetrahydrofuran. The resin solution was cast in thin films onto glass plates and the solvent evaporated in air at 50 C. The dried films after stripping consisted of 25% Neoprene CG, 25% Hycar (DR- and 50% Saran B-118.

The physical properties of films of the example are given in the following Table H:

Moisture vapor transmission-grams water per 24 hours per 100 square inches.

2 Cubic centimeters gas per 24 hours per 100 square inches.

Testing methods used in determining values for Table II Tensile strength.Scott Inclined Plane Tensile Strength Tester. A sample 1 inch long by inch wide is used. Tensile strength as used in Table II is given in pounds per square inch based on orginal cross-section area of the sample.

Elongation-Determined on same machine and sample as tensile strength.

Tear strength.Thwing-Albert Research Type Tearing Tester. An initiated tear through a 1 inch length of film is used. Tear strength is recorded in grams per V 0 inch film thickness.

Moisture vapor transmission-Determined by General Foods Method as described in Modern Packaging, November 1942. Transmission given in grams of water passing through an area of 100 square inches of film in 24 hours.

Oxygen transmission-Determined by method and apparatus described in Paper Trade Journal 118 No. 10, 32 (1944). Transmission recorded as cubic centimeters of gas passing through an area of 100 square inches of film in 24 hours.

No special method of preparing the solution of the synthetic resins and blending agent is necessary. The components can be added either separately or simultaneously to the selected solvent. The mass is preferably agitated until solution is complete. The solution can also be facilitated and hastened by the application of heat.

As shown by the example, the solution can be extruded and the solvent evaporated therefrom, or the solution can be extruded into a bath which is a precipitating agent for the resins and preferably also is miscible with the solvent of the composition.

The solvents which can be employed in the production of shaped articles from the solution are not restricted to those of the examples. When, for example, an article is to be prepared by the process wherein the solvent is evaporated, any volatile solvent in which all of the resins are soluble can be used. When the article is to be prepared by a method wherein the solution is extruded into a precipitating bath, any solvent in which all the resins are soluble, and which preferably also is miscible with the precipitating bath, can be used. Generally, such solvent is volatile so that, upon drying of the article, the residual solvent will be evaporated.

In the embodiment of the invention wherein the solution is extruded into a precipitating bath, the latter is a liquid medium, which precipitates the resin from the solution. The precipitating bath is also one which in admixture with the solvent will form a mixture which is a nonsolvent for the resin. Though many liquid substances and solutions can be used as the precipitating bath, water is preferred because of its economy.

The total resin concentration in the solution is not restricted to that set forth in the example. In general, when the solution is to be processed by a procedure wherein the solvent is evaporated from the shaped article, the total resin (including blending agent) can vary within limits. Usually, a total resin concentration of 10% to 30%, and preferably about 15%, is used.

For wet casting operations, 1. e. when the solution is extruded into a, precipitating bath, a solution viscosity of 10 to 5 seconds by the falling ball method is desired (this represents the time required for a steel ball to fall vertically through 8" of the resin solution). A solids content of approximately 15% to 25% is required to give such a viscosity.

Instead of blending through the use of solvents, the various latices can be mixed and thereafter coagulated and subsequently heated and/or milled.

The films produced by this invention are transparent and can be unvulcanized or vulcanized, as desired. In general, when a vulcanized film is desired, the composition can contain any filler, reinforcing pigment, age resistors, accelerators, and vulcanizing ingredients which are ordinarily used in vulcanizing rubber or synthetic rubber. When such a composition is used, the film, after or during drying, can be vulcanized in the known manner. By the appropriate selection of the vulcanizing agents, one or all of the vulcanizable constituents can be vulcanized to itself or to each other. Vulcanization of a specific constituent depends on the concentration of such ingredient and the use of the vulcanizing agent which will vulcanize only such ingredient.

Various other substances may be included in the formula, such as softening agents, plasticizers, etc., although in general these may not be desirable.

Furthermore, anti-blocking materials, such as paraffin, stearamide, natural waxes, synthetic waxes, stearic acid, cetyl acetamide, ethylene bis palmityl amide, dicetyl ether and their homologues, may be incorporated to improve the surface properties.

As shown by the example, butadiene-acrylonitrile copolymer containing 45% acrylonitrile and vinylidene chloride-vinyl chloride copolymer containing 85% vinylidene chloride are made compatible by a blending agent consisting of polychloroprene. However, the invention is not restricted to such copolymers. The butadieneacrylonitrile copolymer can contain from to 45% acrylonitrile and the vinylidene chloridevinyl chloride copolymer can contain from 82% to 85% vinylidene chloride.

Any solvent of the type hereinbefore described can be used. Tetrahydrofuran is preferred when the solution is made at room temperature. If the temperature at which the solution is compounded is maintained at about 90 C., solvents such as cyclohexanone, isophorone, etc., can be used.

Though the invention has been previously described particularly in connection with the production of film, it is to be understood that the invention is not restricted thereto. The solutions also can be used for the preparation of self-sustaining continuous film in the form of continuous seamless tubing. Likewise, the solutions hereinbefore described can be used in the production of other shaped structures, such as filaments, yarns, fibers, caps, bands, etc. Additionally, the solutions can be employed as a coating composition for the coating of various base materials, such as paper, fabric, metal foil, regenerated cellulose, polyvinyl alcohol, nylon, zein, ethyl cellulose, cellulose acetate, etc. Still further, the solutions can be used as a sealing cement for gasproof seals of resinous sheet materials, as a cement for sealing films of polyvinylidene chloride and its copolymers, as a gasket cement, etc.

Self-sustaining film in the form of continuous sheeting or seamless tubing produced from the components of synthetic resins, herein described, are characterized by high resistance to moisture vapor penetration and to penetration by gases. Because of these properties, a. film of the synthetic resins hereinbefore described is admirably suited for use in wrapping and packaging of any product which is desired to be protected.

In addition to the foregoing properties, a film of the synthetic resins hereinbefore described is transparent, thermoplastic, heat-scalable, resilient, has a high tensile strength, has a fair amount of elongation, is printable, contains no substance which will affect the odor and taste of the product wrapped therein or will migrate from the film into the product wrapped therein, resists exudation of fatty substances, and is highly resistant to puncture, all of which properties render the material particularly suitable for packaging of wrapping of ioodstufis.

Herein and in the claims the proportions are by weight unless otherwise specified.

In the claims, the term consisting essentially of is intended to cover the named ingredients with or without the modifying ingredients herein disclosed.

Since it is obvious that various changes and modifications may be made in the above description without departing from the nature or spirit thereof, this invention is not restricted thereto except as set forth in the appended claims.

We claim:

1. Formed structures consisting essentially of 25% of a synthetic resin formed of a rubbery copolymer of %-55% butadiene and 25 %-45% acrylonitrile, 50% of a copolymer of 18%-15% vinyl chloride and 82 %-85% vinylidene chloride, and 25% of a blending agent consisting of poly chloroprene whereby said copolymers being normally incompatible are made compatible.

} 2. Formed structures consisting essentially of 25% of a synthetic resin formed of a rubbery copolymer of 55% butadiene and 45% acrylonitrile, 50% of a copolymer of 18% vinyl chloride and 82% vinylidene chloride, and 25% of a blending agent consisting of polychloroprene whereby said copolymers being normally incompatible are made compatible.

3. Self-sustaining film consisting essentially of 25% of a synthetic resin formed of a rubbery copolymer of 75%55% butadiene and 25%-45% acrylonitrile, 50% of a copolymer of 18%-15% vinyl chloride and 82 %-85% vinylidene chloride, and 25% of a blending agent consisting of polychloroprene whereby said copolymers being normally incompatible are made compatible.

4. Self-sustaining film consisting essentially of 25% of a synthetic resin formed of a rubbery copolymer of 55% butadiene and 45% acrylonitrile, 50% of a copolymer of 18% vinyl chloride and 82% vinylidene chloride, and 25% of a blending agent consisting of polychloroprene whereby said copolymers being normally incompatible are made compatible.

RALPH J. SIGNER. KEITH F. BEAL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,247,154 Geiger et a1 June 24, 1941 2,319,959 Tierney May 25, 1943 2,330,353 Henderson Sept. 28, 1943 2,445,727 Kinzinger July 20, 1948 2,459,874 Fay Jan. 25, 1949 2,462,029 Perry Feb. 15, 1949 2,552,904 Newberg et al May 15, 1951 FOREIGN PATENTS Number Country Date 577,860 Great Britain June 4, 1946 599,937 Great Britain Mar. 24, 1948 OTHER REFERENCES Garvey et al., Ind. and Eng. Chem. 36 Mar. 1944, PP. 209-211. 

1. FORMED STRUCTURES CONSISTING ESSENTIALLY OF 25% OF A SYNTHETIC RESIN FORMED OF A RUBBERY COPOLYMER OF 75%-55% BUTADIENE AND 25%-45% ACRYLONITRILE, 50% OF A COPOLYMER OF 18%-15% VINYL CHLORIDE AND 82% VINYLIDENE CHLORIDE, AND 25% OF A BLENDING AGENT CONSISTING OF POLYCHLOROPRENE WHEREBY SAID COPOLYMERS BEING NORMALLY INCOMPATIBLE ARE MADE COMPATIBLE. 